Re: Temporal database - no end date

Marshall wrote:
> Nothing in the last two paragraphs has any relevance to modeling
> continua that I can detect. Again, we model the reals with floating
> point, and it works just fine, even though the reals have the power
> of the continuum and floating point doesn't. If we want to bring it
> back to time, then we have to consider that time in the computer
> has a machine-defined resolution, and that makes time in the computer
> discrete, regardless of anything Einstein said about the real world.
> Java models time with a 64 bit int, and that gives you millisecond
> resolution over half a billion year span. That's good enough for my
> apps.

 Sorry.

 I'm with Joe on this one. And I am puzzled why it is that so many of you who usually decry mixing logical and physical models are missing his point. Joe constructs an argument by observing the logical properties of the time domain and the need to reason about it correctly, and you all come back with "physical computers can't do that". I call bullshit!

 For a practical turn, try computing statistical results involving time using a chronon model.

  'What is the mean time to failure?', 'On Date X, we adopted a new manufacturing process. Has this affected the variance of our failure intervals?'. Try computing any of that using integers, and I will find an application where your algorithm will return horribly wrong answers.

  If your model of time can't reason in the abstract about time--Joe's analogy with rational and irrational numbers is spot on--then you don't really have an answer. Models of time that divide the continium into discrete units, and then force all intervals, aggregations and the results of any operation into that model, just don't work. Modeling time using intervals, and being very careful about your implementation, is simply more general. Received on Fri Jan 19 2007 - 19:41:56 CET